1. Field of the Invention
The present invention relates to a tray for holding a plurality of can ends while they are being conveyed.
2. Description of the Prior Art
It has heretofore been known to convey a plurality of arrays of stacked can ends stored in a storage box.
Japanese laid-open utility model publication No. 3-15341 discloses such a storage box for storing can ends. The disclosed storage box is substantially in the shape of a rectangular parallelepiped that comprises a rectangular bottom plate and upstanding wall plates extending from peripheral edges of the bottom plate. Can ends are manually stored into the storage box by the worker. Specifically, horizontal arrays of can ends are successively placed on the bottom plate of the storage box. After the bottom plate is covered with one layer of can end arrays, another layer of horizontal arrays of can ends is piled up on the lower layer. Therefore, the storage box holds vertically successive layers of horizontal arrays of can ends.
Horizontal arrays of can ends may be efficiently placed into and removed from the storage box by a robot having a gripper. The gripper grips an array of can ends and takes it into and out of the storage box.
When the storage box stores can ends, it holds them in vertically successive layers of horizontal arrays, as described above. Therefore, adjacent can end arrays are closely held against each other in the storage box. The can end arrays that are closely packed in the storage box prevent the gripper from being inserted between the can end arrays. Consequently, it would be difficult for the robot to take can ends automatically into and out of the storage box.
The opposite can ends of each of the can end arrays stored in the storage box are held against the respective opposite wall plates thereof. When one of the can end arrays is removed from the storage box, a space is created laterally of those can end arrays which are positioned adjacent to the removed can end array. The remaining can end arrays tend to flex convexly toward the space and hence to be deformed out of a desired shape.
Since the can end arrays are held in contact in the storage box, the contacting can end arrays are liable to damage each other when vibrated during shipment.